纳米碳酸钙/二氧化硅复合粒子的制备及其在丁苯橡胶中的应用

将纳米碳酸钙的制备和表面包覆工艺融为一体,以硅酸钠为无机硅源,采用溶胶沉淀法制备出具有核壳结构的纳米碳酸钙/二氧化硅复合粒子,在纳米碳酸钙的表面包覆了一层致密的二氧化硅膜。采用TEM、红外光谱（FT-IR）、TG、XRD、BET、吸油值测定等手段对复合粒子的大小、形貌、化学组成、结构及表面性质进行了分析和表征。将复合粒子填充于丁苯橡胶,能显著提高丁苯橡胶（SBR）硫化胶的拉伸性能和撕裂性能。当填充量为75份时,拉伸强度最大,为13.6 MPa。     

Synthesis of shape memory polyurethane/clay nanocomposites and analysis of shape memory,thermal, and mechanical properties

In this study, shape memory polyurethane/clay nanocomposites were synthesized by using two‐step in situ polymerization. The effects of nanoparticle content on mechanical, thermal, and shape memory properties were studied. Soft and hard segments of polyurethanes were based on polycaprolactone (PCL) diol and 4,4′‐diphenylmethane diisocyanate/1,4‐butanediol molar ratio with 70/30, respectively. The differential scanning calorimetry, tensile test, dynamic mechanical thermal analysis, parallel plate rheometer, and X‐ray diffraction were used to evaluate the properties of the nanocomposites. To evaluate shape memory properties, a tensile device equipped with a thermal chamber was used. Glass transition temperature of soft segments has been increased by nanoclay loading. Addition of nanoclay to polyurethane matrix caused to disrupt ordering in hard domains, decrease in elongation and tensile strength. The results show that crystallinity of soft segments and dispersion of nanoparticles affect on the mechanical properties and shape memory behavior of nanocomposites, distinctly. Nanocomposite containing 1 wt% shows the best shape memory properties. POLYM. COMPOS., 2012. © 2012 Society of Plastics Engineers     

Studies on the effect of silicon carbide nanoparticles on the thermal,mechanical, and biodegradation properties of poly(caprolactone)

In this work, silicon carbide (SiC) nanoparticles were used to reinforce polycaprolactone (PCL). The nanocomposites were prepared by melt‐mixing followed by mould extrusion. The effect of increased SiC loading on the thermal, mechanical, and dynamic mechanical properties was investigated using differential scanning calorimetry, tensile testing, and dynamic mechanical analysis (DMA), respectively. The morphology and chemical interactions were carried out by scanning electron microscopy and Fourier transform infrared spectroscopy (FTIR), respectively. The SiC nanoparticles were fairly well dispersed in the PCL matrix. FTIR indicated that there was no chemical interaction between PCL and SiC. The presence of SiC nanoparticles influenced the crystallization behavior of PCL, whereas there was no significant influence on thermal degradation behavior of PCL. Generally, the mechanical properties of the nanocomposite increased with an increase in nanoparticle content. The DMA results showed that the presence of SiC improved the storage modulus of PCL especially at higher SiC loading. Thermogravimetric analysis showed a very small influence of SiC on the thermal stability of PCL. Moreover, the glass transition temperature (T_g) of the nanocomposites shifted to lower temperatures compared to that of neat PCL. The crystal structure was not significantly influenced by the presence of SiC. The biodegradation process of PCL in soil environment delayed in the presence of SiC. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42145.     

Cellulose Nanocrystals/ZnO as a Bifunctional Reinforcing Nanocomposite for Poly(vinyl alcohol)/Chitosan Blend Films: Fabrication,Characterization and Properties

In this study, cellulose nanocrystals/zinc oxide (CNCs/ZnO) nanocomposites were dispersed as bifunctional nano-sized fillers into poly(vinyl alcohol) (PVA) and chitosan (Cs) blend by a solvent casting method to prepare PVA/Cs/CNCs/ZnO bio-nanocomposites films. The morphology, thermal, mechanical and UV-vis absorption properties, as well antimicrobial effects of the bio-nanocomposite films were investigated. It demonstrated that CNCs/ZnO were compatible with PVA/Cs and dispersed homogeneously in the polymer blend matrix. CNCs/ZnO improved tensile strength and modulus of PVA/Cs significantly. Tensile strength and modulus of bio-nanocomposite films increased from 55.0 to 153.2 MPa and from 395 to 932 MPa, respectively with increasing nano-sized filler amount from 0 to 5.0 wt %. The thermal stability of PVA/Cs was also enhanced at 1.0 wt % CNCs/ZnO loading. UV light can be efficiently absorbed by incorporating ZnO nanoparticles into a PVA/Cs matrix, signifying that these bio-nanocomposite films show good UV-shielding effects. Moreover, the biocomposites films showed antibacterial activity toward the bacterial species Salmonella choleraesuis and Staphylococcus aureus. The improved physical properties obtained by incorporating CNCs/ZnO can be useful in variety uses.     

Preparation of chitosan nanoparticles and their application to Antheraea pernyi silk

In this study, a chitosan nanoparticle dispersion solution as a novel multifunctional agent was developed to modify Antheraea pernyi silk. An ionization gelation methodology with chitosan and sodium tripolyphosphate (STPP) was used to prepare the chitosan nanoparticle solution, and then, Fourier transform infrared spectra, laser particle size analysis, and transmission electron microscopy (TEM) were used to characterize the structure and size distribution of the chitosan nanoparticles. The peaks at 3390.7, 1633.7, 1538.2, and 1258.1 cm⁻¹ revealed the reaction between the chitosan and STPP molecules in the chitosan nanoparticles. The average size of the nanoparticles in the aqueous dispersion solution was approximately 20 nm. TEM images clearly showed the round spherical morphology and the distribution of the particles in the solid state. The obtained chitosan nanoparticle dispersion solution was then applied to treat silk filaments and fabric. The results indicate that the surface of the chitosan‐nanoparticle‐treated A. pernyi silk fiber was rougher than that of the chitosan‐treated and untreated ones, and a higher specific surface was achieved. In addition, the antibacterial activity, breaking strength, and wrinkle‐resistance properties of the chitosan‐nanoparticle‐treated A. pernyi silk fabric were also enhanced. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

A study on the properties of PMMA/silica nanocomposites prepared via RAFT polymerization

A number of batch polymerizations were performed to study the effect of pristine nanoparticle loading on the properties of PMMA/silica nanocomposites prepared via RAFT polymerization. In order to improve the dispersion of silica nanoparticles in PMMA matrix, the silanol groups of the silica are functionalized with methyl methacrylate groups and modified nanoparticles were used to synthesize PMMA/modified silica nanocomposites via RAFT polymerization. Prepared samples were characterized by thermogravimetric analysis (TGA), dynamic light scattering (DLS), dynamic mechanical thermal analysis (DMTA), differential scanning calorimetry (DSC) and gel permeation chromatography (GPC). According to results, introduction of modified nanoparticles results in better thermal and mechanical properties than those of pristine nanoparticles. Also, surface modification and increasing silica nanoparticles result in variation of thermal degradation behavior of nanocomposites. The best improvement of mechanical and thermophysical properties is achieved for nanocomposites containing 7 wt. % silica nanoparticles.     

Thin Film Nanocomposites Based on SBM Triblock Copolymer and Silver Nanoparticles: Morphological and Dielectric Analysis

Hybrid organic/inorganic thin film nanocomposites based on poly(styrene)‐b‐poly(butadiene)‐b‐poly(methyl methacrylate) triblock copolymer and silver nanoparticles are prepared and characterized. In order to improve the compatibility of nanoparticles with the polymeric matrix, their surface is modified with dodecanethiol surfactant, which enables a good dispersion of nanoparticles through the triblock copolymer, without the formation of aggregates. By atomic force microscopy (AFM), the dispersion level of nanoparticles is analyzed, together with their effect on the thin film surface morphology, for nanocomposites up to 15 wt% of nanoparticles. Dielectric properties of nanocomposites are studied by dielectric relaxation spectroscopy (DRS), analyzing the effect of nanoparticles on dielectric properties. Even if conductivity and permittivity of composites increase with nanoparticle content, percolation threshold is found to be at around 15% in volume. Morphologically analyzed nanocomposites are, in this way, below the threshold.     

Thermoplastic polyurethane and nitrile butadiene rubber blends with layered double hydroxide nanocomposites by solution blending

Polymer blending coupled with nanofillers has been widely accepted as one of the cheaper methods to develop high‐performance polymeric materials for various applications. In the present work, dodecyl sulfate intercalated Mg? Al‐based layered double hydroxide (DS‐LDH) was used as nanofiller in the synthesis of polyurethane blended with nitrile butadiene rubber (PU/NBR; 1:1 w/w) nanocomposites, which were subsequently characterized. X‐ray diffraction (XRD) and transmission electron microscopy (TEM) confirmed the partial dispersion of Mg? Al layers in PU/NBR blends at lower filler content followed by aggregation at higher filler loading. In comparison to the neat PU/NBR blend, the tensile strength (156%) and elongation at break (21%) show maximum improvement for 1 wt% filler loading. The storage and loss moduli, thermal stability and limiting oxygen index of the nanocomposites are higher compared to the neat PU/NBR blend. Glass transition temperature and swelling measurements increase up to 3 wt% DS‐LDH loading in PU/NBR compared to either neat PU/NBR or its other corresponding nanocomposites. XRD and TEM analyses indicate the partial distribution of DS‐LDH in PU/NBR blends suggesting the formation of partially exfoliated nanocomposites. The improvements in mechanical, thermal and flame retardancy properties are much greater compared to the neat blend confirming the formation of high‐performance polymer nanocomposites. Copyright © 2009 Society of Chemical Industry     

Hybrid films of polyimide containing in situ generated silver or palladium nanoparticles: Effect of the particle precursor and of the processing conditions on the morphology and the gas permeability

Hybrid organic/inorganic films have been prepared using different complexes soluble in a (BTDA/4,4′-ODA) poly(amic acid) solution. A silver based complex and two palladium based complexes were used and the metallic nanoparticles were formed by a single step process during the cure cycle applied to the film. Depending on the complex or the curing conditions used, either the nanoparticles formed were uniformly dispersed in the nanocomposite films, or the particles were also located at the film surface. The presence of the nanoparticles, whatever their composition, led to a decrease of the thermal degradation temperature in air atmosphere. The presence of 15 wt% of crystalline silver particles did not induce significant variation of the glass transition temperature and of the gas transport properties demonstrating low nanoparticle/matrix interactions. On the contrary, a pronounced effect in reducing the gas permeability for a wide variety of gases was observed for the nanocomposites containing the palladium based nanoparticles and this even for low palladium amount (5 wt%). Specific interactions between hydrogen and the Pd based nanoparticles were evidenced and the gas transport properties were discussed as a function of following parameters: the gas nature, the nanoparticle structure and composition, the developed morphology and the particle/matrix interactions.     

Study on glass transition temperature and mechanical properties of cadmium sulfide/polystyrene nanocomposites

The cadmium sulfide/polystyrene (CdS/PS) nanocomposites with concentration (0, 2, 4, 6, and 8) wt% of CdS nanoparticles were prepared by solution casting method and characterized through fourier transform infrared spectroscopy (FTIR) and transmission electron microscopy (TEM) measurements. The particle size of nanoparticles is found to be around 15 nm. Glass transition and mechanical behavior of CdS/PS nanocomposites were investigated using dynamic mechanical analyzer (DMA). The mechanical properties such as Young's modulus and tensile strength were determined at room, as well as at elevated temperatures through their stress–strain curves. The result shows that glass transition temperature (T_g) is shifted toward the higher temperature after the addition of CdS nanoparticles. The mechanical properties increased at low wt% loading of CdS nanoparticles and decreased for higher wt% loading of CdS nanoparticles. It was also found that mechanical properties decline with increase in the temperature. POLYM. ENG. SCI., 2013. © 2012 Society of Plastics Engineers     

Rheology,mechanical properties,and biodegradation of poly(ε‐caprolactone)/silica nanocomposites

Biodegradable poly(ε‐caprolactone) (PCL)/silica nanocomposites containing 1–9 wt% silica nanoparticles were prepared by melt compounding in this work. The rheology, mechanical properties, and biodegradation were investigated. PCL/silica nanocomposite shows a high percolation threshold, which is between 7 and 9 wt%. Once percolation network structure forms, the long‐range motion of PCL chains is highly restrained. From the results of mechanical tests, the tensile strength, modulus, and yield strength of the nanocomposites are enhanced by the incorporation of silica nanoparticles. Moreover, it is interesting to find that the biodegradation rates have been enhanced obviously in the PCL/silica nanocomposites than in neat PCL, which may be of great use for the practical application of PCL. POLYM. COMPOS., 34:1620–1628, 2013. © 2013 Society of Plastics Engineers     

Facile preparation of poly(ε-caprolactone)/Fe3O4@graphene oxide superparamagnetic nanocomposites

The main goal in this work was to prepare and characterize a kind of novel superparamagnetic poly(ε-caprolactone)/Fe₃O₄@graphene oxide (PCL/Fe₃O₄@GO) nanocomposites via facile in situ polymerization. Fabrication procedure included two steps: (1) GO nanosheets were decorated with Fe₃O₄ nanoparticles by an inverse co-precipitation method, which resulted in the production of the magnetite/GO hybrid nanoparticles (Fe₃O₄@GO); (2) incorporation of Fe₃O₄@GO into PCL matrix through in situ polymerization afforded the magnetic nanocomposites (PCL/Fe₃O₄@GO). The microstructure, morphology, crystallization properties, thermal stability and magnetization properties of nanocomposites were investigated with various techniques in detail. Results of wide-angle X-ray diffraction showed that the incorporation of the Fe₃O₄@GO nanoparticles did not affect the crystal structure of PCL. Images of field emission scanning electron microscope and transmission electron microscopy showed Fe₃O₄@GO nanoparticles evenly spread over PCL/Fe₃O₄@GO nanocomposites. Differential scanning calorimeter and polar optical microscopy showed that the crystallization temperature increased and the spherulites size decreased by the presence of Fe₃O₄@GO nanoparticles in the nanocomposites due to the heterogeneous nucleation effect. Thermogravimetric analysis indicated that the addition of Fe₃O₄@GO nanoparticles reduced the thermal stability of PCL in the nanocomposites. The superparamagnetic behavior of the PCL/Fe₃O₄@GO nanocomposites was testified by the superconducting quantum interference device magnetometer analysis. The obtained superparamagnetic nanocomposites present potential applications in tissue engineering and targeted drug delivery.     

油酸修饰纳米CaCO3对PP结晶行为和力学性能的影响

Oleic acid (OA)-modified CaCO3 nanoparticles were prepared using surface modification method. Infrared spectroscopy (IR) was used to investigate the structure of the modified CaCO3 nanoparticles, and the result showed that OA attached to the surface of CaCO3 nanoparticles with the ionic bond. Effect of OA concentration on the dispersion stability of CaCO3 in heptane was also studied, and the result indicated that modified CaCO3 nanoparticles dispersed in heptane more stably than unmodified ones. The optimal proportion of OA to CaCO3 was established. The effect of modified CaCO3 nanoparticles on crystallization behavior of polypropylene (PP) was studied by means of DSC. It was found that CaCO3 significantly increased the crystallization temperature, crystallization degree and crystallization rate of PP, and the addition of modified CaCO3 nanoparticles can lead to the formation of β-crystal PP. Effect of the modified CaCO3 content on mechanical properties of PP/CaCO3 nanocomposites was also studied. The results showed that the modified CaCO3 can effectively improve the mechanical properties of PP. In comparison with PP, the impact strength of PP/CaCO3 nanocomposites increased by about 65% and the flexural strength increased by about 20%.     

纳米SiO2粒子对低熔点混合硝酸盐热物性影响

为探究纳米粒子对低熔点混合硝酸盐热物性的影响规律,采用高温熔融分散法将平均粒径20 nm的SiO₂纳米粒子以1%（质量）比例直接分散到混合熔盐[Ca（NO₃）₂·4H₂O-KNO₃-NaNO₃-LiNO₃]中得到不同分散条件下的熔盐纳米复合材料。采用同步热分析仪（DSC）与激光闪射仪（LFA）测量熔盐纳米复合材料比热容与热扩散系数,进而得到热导率。分析发现,600 r/s搅拌速率下熔盐纳米复合材料热物性随分散时间（15,45,90,120和150 min）发生明显变化。比热容、热扩散系数和热导率在分散45 min时提高率最大,平均提高率分别为11.5%,12.9%和26.4%。扫描电镜（SEM）观察到熔盐纳米复合材料表面有大量特殊结构（类似于链状或条状）存在。这些具有高比表面积和表面自由能的特殊结构可能是熔盐纳米复合材料热物性提高的关键。     

Polypropylene/silica nanocomposites prepared by in-situ melt ultrasonication

A novel process using ultrasonic irradiation to enhance nanosilica dispersion in polypropylene-based nanocomposites has been proposed and investigated. The nanocomposites were isotactic polypropylene reinforced with silica nanoparticles at 3 wt% loading level. Ultrasonic processing in the melt state is an effective method for improving nanosilica dispersion. The effectiveness of the proposed ultrasonic processing technique on polypropylene nanocomposites was evaluated by XRD and transmission electron microscopy (TEM). Poly(propylene-g-maleic anhydride) copolymer (PP-g-MAH) containing 5 wt% maleic anhydride content was added to nanocomposites at 0.5 wt% concentration based on silica content. PP-g-MAH plays an important role in nanosilica dispersion in polymer matrix and interface interaction. The reaction of maleic anhydride groups with the hydroxyl groups on the surface of nanosilica was characterized by FTIR spectrum. The final nanocomposites result in a further enhancement of mechanical properties because of silica agglomerate reduction and improving interface combination, even loading level being much lower than that of ordinary fillers in conventional composites. POLYM. COMPOS., 2009. © 2009 Society of Plastics Engineers     

Nanoparticle Network Formation in Nanostructured and Disordered Block Copolymer Matrices

Incorporation of nanoparticles composed of surface-functionalized fumed silica (FS) or native colloidal silica (CS) into a nanostructured block copolymer yields hybrid nanocomposites whose mechanical properties can be tuned by nanoparticle concentration and surface chemistry. In this work, dynamic rheology is used to probe the frequency and thermal responses of nanocomposites composed of a symmetric poly(styrene-b-methyl methacrylate) (SM) diblock copolymer and varying in nanoparticle concentration and surface functionality. At sufficiently high loading levels, FS nanoparticle aggregates establish a load-bearing colloidal network within the copolymer matrix. Transmission electron microscopy images reveal the morphological characteristics of the nanocomposites under these conditions.     

Near‐infrared activation of semi‐crystalline shape memory polymer nanocomposites

Recently, indirect activation of the shape memory effect has become an increasingly popular triggering modality for shape memory polymer biomaterials. Amongst the known methods for remote activation, near‐infrared radiation (NIR) remains relatively unexplored, specifically for semicrystalline materials, which possess sharp thermal transitions. Herein, poly(ε‐caprolactone) (PCL) networks were photo‐polymerized from branched precursors doped with 150 nm surface modified gold nanoshells with a surface plasmon resonance of approximately 800 nm. The effect of nanoparticle loading on the thermal, mechanical, and shape memory properties of the PCL matrix were examined. The PCL nanocomposites exhibited excellent shape fixation and nearly quantitative shape memory recovery in response to low intensity NIR irradiation. Further, the heat dissipated by the irradiated nanocomposites to the surrounding medium was found to reach a maximum at biologically relevant temperatures. As such, this nanocomposite system represents a highly attractive candidate for many biomedical shape memory applications. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 4551–4557, 2013     

Structure-property relations of 55 nm particle-toughened epoxy

55-nm rubber particles significantly toughened two epoxy systems without loss of Young’s modulus, tensile strength and glass transition temperature. Transmission Electron Microscopy (TEM) showed that the nanoparticles are uniformly dispersed in matrix and have blurred interface with epoxy. 5 wt% rubber nanoparticles increased the critical strain energy release rate (G_1c) of Jeffamine D230 (J230)-cured epoxy from 175 J/m² to 1710 J/m², while the 10 wt% increased G_1c of diaminodiphenyl sulfone (DDS)-cured epoxy from 73 J/m² to 696 J/m². This is explained by comparing the surface-surface interparticle distance and total particle surface of nanocomposites with those of composites. The higher the matrix stiffness, the more nanoparticles needed for toughening. Although the 10 wt% J230-cured nanocomposite showed a 50% larger size of stress-whitened zone than the 5 wt% J230-cured nanocomposite, the 5 wt% nanocomposite showed a higher toughness. These nanoparticles were found to pose barriers to the vibration of crosslinked matrix molecules, leading to higher glass transition temperatures. While the matrix shear banding caused by nanoparticle expansion and growth is the major toughening mechanism for the J230-cured nanocomposites, the matrix plastic void growth and deformation are most probably the major mechanisms for the DDS-cured system. Under tensile loading, the nanoparticles in the DDS-cured epoxy created fibrils of 100-200 nm in diameter and 3-5 μm in length. TEM analysis in front of a subcritically propagated crack tip showed a number of voids of 30-500 nm in diameter in the vicinity of the crack, implying that rubber nanoparticles expanded, grew and deformed under loading. Unlike conventional epoxy/rubber composites in which all of the rubber particles in the crack front cavitated under loading, only a portion of the nanoparticles in this study expanded to create voids. Huang and Kinloch’s model developed from composites was found not fit well into these nanocomposites.     

Morphology evolution induced by carbon nanotubes on thermal and mechanical characters of semi-crystalline aromatic polyimide

A series of nanocomposites based on a new semi-crystalline polyimide (PI) and multi-walled carbon nanotubes (MWCNTs) were prepared by in situ polymerization. The TEM measurement reveals the improved dispersion of carboxylic acid-functionalized MWCNTs (COOH-MWCNTs) in semi-crystalline PI compared with pristine MWCNTs. The TGA analysis show that the concentration of carboxylic acid groups on the surface of nanotubes is about 4.34 wt%. The FT-IR spectroscopy analysis indicate that the imide rings of the PI interact non-covalently with nanotubes. The Polarized optical microscopy observation reveals significant morphology evolution in semi-crystalline PI induced by MWCNTs. The SEM micrographs suggest the strong interfacial interaction between COOH-MWCNTs and PI main chains, and significant changes in the fracture surfaces morphology. The WAXRD measurements reveal that COOH-MWCNTs promote the semi-crystalline PI crystallinity and structure change. COOH-MWCNTs can more efficiently improve the mechanical and thermal properties of resulting nanocomposites than pristine MWCNTs. COOH-MWCNT/PI nanocomposites show increases of Young’s modulus and yield strength, as high as 20–30 %, without sacrificing the elongation at break at loadings of 0.5 wt% nanotubes. Furthermore, with increasing the loadings of COOH-MWCNTs to 1.0 wt%, Young’s modulus and yield strength decrease due to nanotube aggregation, but elongation at break increase about 46 %. An abrupt increase of elongation at break in pristine MWCNT/PI nanocomposites was also registered at nanotubes loadings increasing from 0.5 to 1 wt%. These results indicate that the properties of semi-crystalline PI nanocomposites reinforced with carbon nanotubes are not only determined by the dispersion of nanotubes in the PI matrix and their interfacial interactions, but also by the crystalline phase morphology evolution in the PI matrix.     

Antibacterial Nanocomposite of Poly(Lactic Acid) and ZnO Nanoparticles Stabilized with Poly(Vinyl Alcohol): Thermal and Morphological Characterization

The effect of polyvinyl alcohol (PVA) as a surface coating agent on the antibacterial and thermal properties of polylactic acid (PLA)/ZnO nanocomposites prepared by melt blending was investigated. The ZnO nanoparticles were coated and stabilized with PVA using a solvothermal method. Nanocomposites were prepared with different ZnO nanoparticle content: 1, 3 and 5 wt.%. Electron transmission microscopy and Fourier transform infrared spectroscopy showed the presence of a layer around the nanoparticles and the interaction between nanoparticles and PVA, respectively. DSC analysis revealed that the thermal properties of the nanocomposites were not affected by the coating of ZnO nanoparticles with PVA. The PLA/ZnO nanocomposites with coated nanoparticles presented better antibacterial activity than those containing uncoated nanoparticles.